The present invention relates to communication systems. More specifically, the present invention relates to radio frequency (RF) communication systems for data communication between portable electronic devices such as in continuous glucose monitoring systems.
Continuous glucose monitoring systems generally include a small, lightweight battery powered and microprocessor controlled system which is configured to detect signals proportional to the corresponding measured glucose levels using an electrometer, and RF signals to transmit the collected data. When the microprocessor is active or when the system is in the process of processing or transmitting data, the battery power supply may display a loading effect commonly referred to as “drooping” due to the current consumption of the microprocessor operation or the transmit function compared to the average current draw level.
The voltage drooping may occur when the processor (or controller) for the transmitter initiates and performs a configured procedure, or alternatively, in the case where the RF transmitter initiates data transmission. For example, the processor may draw a small amount of current in idle state (for example, 1 μA), while in active processing mode, it may draw as much as 2 mA. Additionally, the RF transmitter may draw approximately 10 mA during data transmission state.
The drooping effect is particularly prominent after a portion of the available battery energy has been consumed (that is, the battery energy is partially discharged) and is typical for small batteries where size, weight and power density are optimized versus peak current capacity. This, in turn, may have a negative impact on the processing of detected signals such as by signal degradation or data loss, and importantly, may adversely affect the delicate electrometer and the analog circuitry in the transmitter unit of the monitoring system. More specifically, when the analog front end circuitry in the transmitter of the monitoring system is disturbed, there may be a several second delay when the data may be unusable and a longer delay (for example, on the order of 10 seconds) when the data may be unreliable or beyond the tolerance range of desired accuracy.
In view of the foregoing, it would be desirable to isolate the delicate electrometer and the analog circuitry of the monitoring system, for example, in the transmitting side, from the adverse effects of battery voltage drooping using simple, low cost and low noise approaches, in contrast to the existing techniques using, for example, a DC to DC converter which typically has higher cost as well as higher noise.